Generally, some work machines have a crawler traveling apparatus, such as a hydraulic excavator and a tractor, which are used as a traveling apparatus for transporting an apparatus body. Such a crawler traveling apparatus is provided with a drive sprocket (drive wheel) at one end in the forward and backward directions and an idler wheel (driven wheel) at the other end at both left and right sides of the traveling frame. The traveling frame is secured at the lower part of the body, and a crawler belt is wound around both of the wheels (drive and driven). The crawler belt moves endlessly around both the wheels in line with driving rotations of the drive sprocket, and the apparatus body travels forward or backward. In this case, with respect to the crawler belt wound around both the wheels, a plurality of lower rollers (grounding rollers, lower rolling rollers, and track rollers) are provided on the ground side (lower portion), and upper rollers (upper rolling rollers and carrier rollers) are provided on the non-ground surface side (upper portion). The rollers guide movement of the crawler belt.
The above-described upper rollers are supported by a support receiving member integrally secured on the traveling frame. There is, for example, a type in which both-end portions of the roller shaft are supported by the support receiving member. Such types as shown in, for example, FIGS. 7(A) and (B) have been publicly known as such a prior art structure. The support receiving member 21 is structured so that an opening 21a, into which the upper roller 22 is loosely fitted, is formed at the central portion of a rectangular flat-shaped member. The support receiving member 21 is provided with a surrounding roller supporting portion 21b with opposing side surfaces to support the roller shaft and a pair of forward and backward extending plate-shaped coupling pieces 21c for coupling the roller supporting portions 21b to the traveling body frame.
In the above-described prior art support receiving member 21, because each coupling piece 21c is formed to be like a long plate-shaped member extending in the roller shaft direction, that is, in the direction orthogonal to the traveling direction of the crawler belt, there are cases where mud and sand may enter between a pair of the forward and backward coupling pieces 21c where the work machine travels on soft ground in a mountainous area. Once mud and sand enter, it is difficult to discharge the mud and sand. In particular, in the winter season, the above-described mud and sand that has entered between the coupling pieces 21c may become frozen, wherein there occurs the problem that smooth rotation of the upper rollers 22 is hindered.
Therefore, it is proposed that, as shown in FIG. 7(C), the support receiving member is formed as a segmented type. Each end portion of the roller shaft is, respectively, supported by one pair of supporting receiving members 23 so as not to accumulate mud and/or sand between the support receiving members 23. However, in this type of support, because a roller supporting portion 23a for supporting the roller shaft and coupling piece 23b for coupling the traveling body frame are integrally formed, it is difficult to fine-adjust the attaching position of the upper roller shaft on the support receiving members 23 which results in another problem, that is, the positional accuracy of the upper rollers cannot be secured. In any one of the above examples, there are shortcomings incidental to the type of support. Accordingly, the invention is meaningful in view of solving the above-described problems and shortcomings.